Which of the following structures form the bulk of each of the testis?

a. Decrease in hydrogen ions: A decrease in hydrogen ions (H+) would indicate a condition of alkalosis, not acidosis.

b. Decrease in carbon dioxide: A decrease in carbon dioxide (CO2) usually leads to respiratory alkalosis because CO2 is acidic in nature.

c. Decrease in ketones: Ketones are acidic compounds, and their decrease is not associated with acidosis. In fact, an increase in ketones can cause ketoacidosis.

d. Decrease in bicarbonate ions: Bicarbonate (HCO3-) is a base, and a decrease in its concentration can lead to metabolic acidosis, as it reduces the buffering capacity of the blood against excess H+.

a: Basal ganglia - The basal ganglia are involved in motor control and coordination but not in respiratory regulation.

b: Parietal lobe - The parietal lobe is involved in sensory processing and spatial awareness but not in respiratory regulation.

c. Medulla: The medulla oblongata, specifically the respiratory center within it, is responsible for the involuntary control of respiration, including setting the basic rhythm of breathing and responding to changes in blood pH and oxygen levels.

d: Hypothalamus - The hypothalamus regulates various physiological processes, including temperature regulation and hormone secretion, but not respiration.